diff --git a/tests/test_availability_api.py b/tests/test_availability_api.py
index d76f9c5..3b2b812 100644
--- a/tests/test_availability_api.py
+++ b/tests/test_availability_api.py
@@ -14,9 +14,11 @@ now = datetime.utcnow()
 url = "https://example.com/"
 user_agent = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.99 Safari/537.36"
 
-rndstr = lambda n: "".join(
-    random.choice(string.ascii_uppercase + string.digits) for _ in range(n)
-)
+
+def rndstr(n):
+    return "".join(
+        random.choice(string.ascii_uppercase + string.digits) for _ in range(n)
+    )
 
 
 def test_oldest():
@@ -58,7 +60,7 @@ def test_invalid_json():
     """
     with pytest.raises(InvalidJSONInAvailabilityAPIResponse):
         availability_api = WaybackMachineAvailabilityAPI(url="", user_agent=user_agent)
-        archive_url = availability_api.archive_url
+        _ = availability_api.archive_url
 
 
 def test_no_archive():
@@ -74,7 +76,7 @@ def test_no_archive():
         availability_api = WaybackMachineAvailabilityAPI(
             url="https://%s.cn" % rndstr(30), user_agent=user_agent
         )
-        archive_url = availability_api.archive_url
+        _ = availability_api.archive_url
 
 
 def test_no_api_call_str_repr():
diff --git a/tests/test_cdx_snapshot.py b/tests/test_cdx_snapshot.py
index cacdc0f..baea40e 100644
--- a/tests/test_cdx_snapshot.py
+++ b/tests/test_cdx_snapshot.py
@@ -1,7 +1,5 @@
 from datetime import datetime
 
-import pytest
-
 from waybackpy.cdx_snapshot import CDXSnapshot
 
 
diff --git a/tests/test_cdx_utils.py b/tests/test_cdx_utils.py
index a0b5ff4..406e7e6 100644
--- a/tests/test_cdx_utils.py
+++ b/tests/test_cdx_utils.py
@@ -87,10 +87,10 @@ def test_check_collapses():
 
 
 def test_check_match_type():
-    assert None == check_match_type(None, "url")
+    assert check_match_type(None, "url") is None
     match_type = "exact"
     url = "test_url"
-    assert None == check_match_type(match_type, url)
+    assert check_match_type(match_type, url) is None
 
     url = "has * in it"
     with pytest.raises(WaybackError):
diff --git a/tests/test_save_api.py b/tests/test_save_api.py
index 92a1cde..afd3863 100644
--- a/tests/test_save_api.py
+++ b/tests/test_save_api.py
@@ -8,9 +8,11 @@ import pytest
 from waybackpy.exceptions import MaximumSaveRetriesExceeded
 from waybackpy.save_api import WaybackMachineSaveAPI
 
-rndstr = lambda n: "".join(
-    random.choice(string.ascii_uppercase + string.digits) for _ in range(n)
-)
+
+def rndstr(n):
+    return "".join(
+        random.choice(string.ascii_uppercase + string.digits) for _ in range(n)
+    )
 
 
 def test_save():
@@ -24,8 +26,9 @@ def test_save():
     cached_save = save_api.cached_save
     assert cached_save in [True, False]
     assert archive_url.find("github.com/akamhy/waybackpy") != -1
+    assert timestamp is not None
     assert str(headers).find("github.com/akamhy/waybackpy") != -1
-    assert type(save_api.timestamp()) == type(datetime(year=2020, month=10, day=2))
+    assert isinstance(save_api.timestamp(), datetime.datetime)
 
 
 def test_max_redirect_exceeded():
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 88d2eda..6f6d509 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,4 +1,4 @@
-from waybackpy.__version__ import __version__
+from waybackpy import __version__
 from waybackpy.utils import (
     DEFAULT_USER_AGENT,
     latest_version_github,